Sprinkler-alarm apparatus



May 13 1924.

c. c. JOHNSON SPRINKLER ALARM APPARATUS Filed March 29. 1.920

JWVENTOR. 66W C AT T ORNE 1.

Patented May-13, 1924.

UNITED STATES I p 1,494,116 PATENT OFFICE;

CLARENCE c. Jonnsomor METUCHEN, NEWJEBSEY, ASSIGNOR To AMERICAN msmrexcr, TELEGRAPH COMPANY, OFJERSEY CITY, new JERSEY, A CORPORATION or NEW JERSEY.

Application filed March To all whom it may concern:

Be it known that I, .CLARENGE C. JOHN- soN, a citizen of the United States of America, and a resident of Metuchen, Middlesex County, New Jersey, have invented certain new and useful Improvements in Sprinkler Alarm Apparatus, of which the following is a specification.

My invention relates to improvements in so-called sprinkler supervisory systems, i. e., systems designed togivean alarm in the event of occurrence of water flow. My invention relates particularly. to means for preventing false alarms being given as a result of water hammer or fluctuations in pressure of the water supply. Heretofore alarm systems for this general purpose have been devised, but have failed to meet the conditions which frequently obtain in actual service; for example it not infrequently happens that the pressure in a city main supplying water to sprinkler systems varies during different times of the day by as much as one hundredpounds; such varia tion being due not at all to water hammer, but being incident to the 'use'. made'of the water in the supply .system. 'My invention comprises means whereby false alarms are avoided even under extreme conditions of pressure variation. 1

The object of my invention is to provide a simple sprinkler supervisory system, wherein false alarms shall not be caused by water hammer, or other variations of pressure,including excessive variation in pressure in the supply to the system.

I will now proceed to describe my invention with reference to the accompanying drawing, illustrating one embodiment thereof, and will then point out the novel features in claims.

In said drawings:

Figure 1 is a diagrammatic elevation and partial sectional view of piping valves, etc, embodying my invention, and

Figure 2 is a detail elevation and partial section, on a larger scale, ofthe contact device employed in the system.

In the drawings, 1 designates a supply pipe, for example, a city main subject to extreme fluctuations of pressure, and 2 designates a riser, forming a part of the sprinkler system to be supervised, and from,

which similar pipes containing sprinkler heads branch oft" at diiferent levels. Near SPRINKLER-ALARM APPARA'rfis. 1.

29, 1920. Serial 110461526;

On opposite sides of the check valve 3 are pipes 5 and 6, leading to a water chamber 7 provided with a wall 3 extending across said chamber and provided with an orifice across which is located a diaphragm 8, which diaphragm actuates a stem 8 and a lever 9 having at its outer end mean'sfor operating electrical contacts enclosed within a chamber 9. Pipes 5 and 6 connect to the chamber 7 on opposite sides of the diaphragm 8. ,In pipe 5 there is a washer 10 having a small or restricted opening 10. In water chamber 7 there is an air chamber 11, i. 'e., a chamber closed at the top and in which there will be a cushion of 'ai'r above the normal level of the water in chamber 711. This cushioning chamber connects 5is connected. In chamber? there areprovided diaphragm guards 8 and 8, the ,function of which is to prevent rupture of the diaphragm. Contact-operating rod 9 is mounted in a flexible mounting 12 permitting oscillation of rod 9 asif that rod were pivoted at that point; and at the outerend of rod 9, and within case 9 there are contact devices 13, the nature of which it is not necessary to describe particularly, as this arrangement of contact devices is well known in this art. For present purposes it is sufiicientto assume that if rod be oscillated by outward movement (i. e, movement to the left of Figure 1) of the diaphragm 8, the contact device .13 will beo'perated in a sense to cause transmission of an alarm.

The operation of the system is as follows: In the event of opening of one or more of the sprinkler heads 14, the water flow will commence, of course, check valve 3 opening to permit this flow, but since the flow is continuous, pressure will be communicated through pipes 5 and 6 to both sides of the diaphragm 8, and the pressure communicated through pipe 6 will be less than that communicated through pipe 5, due to restriction offered by the check valve 3, so that the diaphragm 8 will be moved slightly to the left of the position shown in Figure 1, the rod 9 being thereby caused to operate the contact devices 13, so that an alarm is transmitted. But if, instead of one or more of the sprinkler heads 14 opening, or aq steady leak Occurring, there be a sudden and brief use due to sudden and momentary rise in pressure in main 1, such as thesephragm, owing to the restriction 10 in pipe 5, and owing to the elasticity of the air imprisoned in chamber 11 and consequent ability of chamber 11 to absorb brief rises in pressure communicated through pipe 5, so preventing an immediate rise in pressure on the right hand side of the diaphragm as on the left handside. As a result diaphragm 8 will be moved, if at all, to the right of Figure 1, which movement causes no actuation of the contact devices 13.

In other words, upon the opening ofone or more of the sprinkler heads, or upon the development of a steady leak above check valve 3, the fall in pressure resulting is communicated immediately through pipe 6 to the left hand side of the diaphragm 8, while for a moment the pressure on the right hand side of that diaphragm remains nearly as before, owing to expansion, of air in chamber 11 and owing to thefrestrictive action of the small orifice 10; as a result, dia phragm 8 is moved quickly to the left, the

contacts 13 are operated, and an alarm re sults. But upon the occurrence of water hammer, the resulting 'momentary 'rise in pressureis asborbeol, on the right handside of the diaphragm, by the air in chamber 11, and moreover is communicated slowly, because of restricted orifice10 while such rise in pressure is communicated rapidly through pipe 6 to the left-hand side of the diaphragm, as a result ofwhich the diaphragm moves, if at all, to the right, and no actuation of contacts 13 results, and no alarm is sent.

The restricted orifice 10 in restriction'10. and the body of air imprisoned in chamber 11, may be adjusted by adjusting the size of the said restriction orifice 10 and by ad justment of capacity of the air chamber 11, in installation of the system, to meet the most abnormal conditions of sudden variation of pressure in water main 1.

As is obvious, the instant the sudden and momentary increase in pressure in water main 1 passes, or becomesstatic, valve 3 closes and the diaphragm 8, contact-operating rod 9, and the contact devices 13 return to normal condition.

T What I claim is: j

1. The combination with a flow pipe subject to sudden variations of pressure and provided with a check-valve, of fluid-pressure-actuated means comprising a water chamber provided with a separating diaphragm,connections from opposite sides of said diaphragm to said flow pipe on opposite sides of said check-valve, the connection to the flow pipe on the supply side of said check valve having a restriction therein, the connection to the opposite side of the check-valve beingunrestricted, and a cushioning air-chamber interposed between the connection on the supply side and said water chamber.

2. In a supervisory device for a sprinkler system of the type described, the combination with a flow pipe subject to sudden variations of pressure and provided with a checkvalve, of fiuid-pressure-actuated means comprising a water chamber provided with a cushioning air-chamber, a diaphragm dividing the chamber, a single channel connecting the parts of said flow pipe upon opposite sides of said check-valve, said channel comprising connections tosaid chamber upon opposite sides of'said diaphragm, the connection to the flow pipe upon the supply side of the check-valve entering said cushioning chamber, and being provided with a restriction, the other connection being unrestricted.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses.

CLARENCE C. JOHNSON.

Witnesses CATHERINE J. FLEMING, DOUGLAS P. FOWLER. 

